The present invention relates to a brake mechanism.
Preferably disk brakes which are actuated by compressed air, in particular for commercial vehicles, are fastened in each case to a connecting element which is connected fixedly to the wheel axle by a fastening flange of the brake caliper or a brake carrier of the disk brake being screwed to the connecting element.
This type of fastening is shown and described, for example, in EP 0 849 486 A2. Here, the connecting element and the fastening flange of the brake caliper bear with their full surface area against one another, that is to say in an overlapping manner, and are screwed to one another by screws which extend in the axial direction of the wheel axle.
Although satisfactory positioning of the brake caliper is achieved as a result, the exclusively force-transmitting connection is associated with some disadvantages which stand in the way of long-term optimum operation of the disk brake.
During the braking operation, a torque becomes active as a result of the applied braking force or as a result of the friction forces which act on the brake disk, which torque has to be absorbed by the screw connections which in each case comprise a through hole, a threaded hole and a screw, it being possible for the through hole to be provided in the connecting element or fastening flange and for the threaded hole to be provided in the other associated component.
In order for the screw to pass through, the diameter of the through whole has to be greater than the shaft diameter of the screw. In particular in the case of high braking moments which are not transmitted by the force-transmitting connection, this leads to a relative movement of the component which has the through hole with respect to the other components, until the interior of the through hole comes into contact with the screw shaft. As a result, the screws are subjected to shear forces to a considerable extent, which makes corresponding cross-sectional dimensioning necessary which counteracts inexpensive mounting and a weight-optimized construction.
It is also problematic that this type of connection requires a relatively large number of connection screws, which necessitates large bearing faces of the connecting element and the fastening flange.
As a result of the abovementioned relative displacement of the components which are connected to one another during braking, the sliding guide of the brake caliper in a sliding caliper brake can be stressed, which leads to long-term damage of the guide parts. Moreover, in the case of reversing operation, the frequent to and fro displacement of the components can lead to loosening of the screws, as a result of which the operational security can be impaired overall.
One further disadvantage of the known fastening type is the poor accessibility of the screws; as screwing has to take place from the vehicle inner side, mounting and dismantling of the brake is made difficult.
It is known from DE 200 21 587 U1 not to arrange the screws coaxially with respect to the rotational axis of the disk brake, but tangentially with respect thereto. Although this construction makes improved accessibility of the screws possible during mounting and a reduction in the brake weight as a result of the possible smaller bearing faces of the connecting element and the fastening flange, the relative displaceability of the two components with respect to one another during the transmission of the braking moments to the axle still exists, with the above-described disadvantages.
The present invention is therefore based on the object of developing a brake mechanism of the generic type in such a way that it can be manufactured and mounted or dismantled inexpensively, weight reduction of the brake overall is achieved and the operational security is improved.
This object is achieved by a brake mechanism having a connecting element which is fastened to a wheel axle of a motor vehicle or is configured in one piece with the latter, and a fastening flange of a brake caliper or a brake carrier of a disk brake, the fastening flange being fastened to the connecting element, wherein the fastening flange is held in a form-fitting manner on the connecting element in the circumferential direction of the wheel axle.
As a result of this structural configuration, the braking moment is now absorbed by a form-fitting connection and not, as in the prior art, by a force-transmitting connection. Relative displacement of the fastening flange with respect to the connecting element is therefore precluded.
This results first of all in an improvement in the operational security, as, for example in the case of a sliding caliper brake, the guide parts can no longer be stressed with respect to one another and, during reversing operation, loosening of connection screws is precluded.
As they no longer serve to accommodate the screws, but exclusively for the form-fitting connection, the contact faces of the two components can be kept relatively small, which contributes to a weight saving and to the optimization of manufacturing. The same is true analogously for the reduced number of connections screws which is then possible, as these in practice serve only to hold the two components against one another.
The associated reduction in the space requirement makes substantially improved accessibility to the screws possible, with the result that mounting and dismantling of the brake is possible in a substantially simpler manner.
According to one advantageous development of the invention, there is provision for the contact faces of the fastening flange on one side and of the connecting element on the other side to extend in a manner which is oriented obliquely toward the center of the wheel axle, with the result that the respective two contact faces lie in a V shape with respect to one another. Here, the fastening flange in practice forms a wedge which is supported laterally on the connecting elements.
During brake mounting, this V shape makes simple, predefined positioning possible, which likewise simplifies mounting.
Further advantageous refinements of the invention are described and claimed herein.